This invention relates to a developing device that develops a latent image with a developer (for example, a toner) in an image forming apparatus such as an electrophotographic recording device.
In a general electrophotographic recording device, a photosensitive body (i.e., a latent image bearing body) is uniformly charged, and is exposed to the light so that a latent image is formed thereon. The latent image on the photosensitive body is developed (visualized) with a toner that adheres to the latent image. The developed toner image is transferred to a recording medium, and is fixed to the recording medium. Components for causing the toner to adhere to the photosensitive body are integrally constructed as a developing device. The developing device is detachably attached to a main body of the electrophotographic recording device.
A toner container (i.e., a toner cartridge) storing the toner is detachably attached to the developing device, and the toner is supplied from the toner container to the developing device. When the toner container is attached to the developing device, a shutter of the toner container is opened so that the toner (stored in the toner container) falls in the interior of a hopper of the developing device. Such a developing device is disclosed in, for example, Japanese Laid-open Patent Publication No. 2002-72657.
In the conventional developing device, the shutter is kept opened when the toner container is attached to the developing device, and therefore the toner container keeps supplying the toner to the developing device. Accordingly, if the amount of toner consumption is small, the density of the toner in the hopper may increase, and the pressure in the hopper may also increase. The pressure increase in the hopper may cause a failure in forming a thin toner layer (on the photosensitive body) or a failure in charging the toner in the developing device. In such a case, a printing quality may be degraded.